Cooling tower stack assembly



Feb. 12, 1963 .1. G. DE FLON 3,077,008

COOLING TOWER smcx ASSEMBLY Filed May 1. 1959 2 Sheets-Sheet 1 INVENTOR 15144455 6, Def :0

BYWMf Feb. 12, 1963 J. ca. DE FLON COOLING TOWER STACK ASSEMBLY z sheets-shaet 2 Filed May 1. 1959 NVE TOR @4455 6. 0

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3,077,5tl8 CDGLENrTr TGWER STAQK ASdEMELY llamas G. De Finn, Whittier, Calih, assignor to The Floor Corporation, Ltd, has Angeles, (Delhi, a corporation of (Jr-.lifornia Filed May 1, 1959, &1. No. smear Claims. ill. 2tl-.5)

This invention relates generally to the construction of water cooling towers and more particularly has to do with the fabrication of cooling tower stacks within which fans are operable to draw air upwardly from cooling tower chambers for discharge after the air has passed in cooling relation with water sprayed downwardly within the chambers.

It is a major object of the present invention to improve the construction of cooling tower stacks to the end that they may be made extremely strong and rigid for resisting wind loading for example, and also to the end that the boards or batts normally comprising the curved stack wall may be nailed or otherwise attached in position on the curved stack frame with minimum effort. in this regerd, conventional cooling tower stacks are constructed with board or batt siding extending generally vertically, making the stack assembly extremely difficult where the stack walls are not vertical. For example, the venturi shaped stack, which is a subject of the present invention, would be extremely difficult to fabricate were the boards forming the stack walls to be allixed in generally upright positions since they would have to be curved sharply, particularly at the more convergent regions of the venturi stack.

Accordingly, the present invention contemplates the provision of an improved cooling tower stack assembly comprising a frame having a central axis, and elongated boards carried by the frame and forming therein a venturi shaped axial opening, the boards extending in a spiral course about the stack axis. More particularly, the boards forming the upwardly convergent lower portion of the stack opening are enabled to be lengthwise substantially straight as a result of their spiral extent about the stack axis, and as will be brought out, when the boards forming the upwardly converging lower portion of the stack opening have parabolic cross sections in axial vertical planes, the boards may be given a spiral course resulting in their extending substantially straight.

Gther features and objects of the invention include inner and outer layers of boards spiraling in opposite directions about the stack central axis, the stack frame being at the outside of the boards and resisting outward pressure exerted, particularly by the boards forming the upwardly diverging portion of the stack opening, these latter boards having lengthwise curvature about the central axis. Such curvature is relatively slight considering the Width of the boards and therefore they are easily nailed in curved position to form the upper portion of the stack, whereas it would be extremely difiicult to bend the same boards about the sharp curvature in vertical planes at the upwardly converging lower regions of the stack wall. As a result of the construction of the stack described and to be described, the spiral boards exert shear loading upon nails holding them to the frame and in layers, preventing withdrawal of the nails by tension loads exerting thereagainst.

These and other objects and advantages of the invention, as well as the details of an illustrative embodiment, will be more fully understood from the following detailed description of the drawings, in which:

FIG. 1 is a plan view of the stack shown in FIG. 2;

FIG. 2 is an external elevation showing the stack in partly assembled form; and

FIG. 3 is an enlarged vertical section through a portion 3&771993 Patented Feb. 12, 1963 of the stack showing certain details of construction thereof.

In the drawings the stack assembly is shown to include a frame generally indicated at 11 having a central axis 12, and elongated boards indicated at 13, the latter being carried by the frame and forming therein a venturi shaped axial opening 14, which is upwardly convergent in the region 15 and upwardly divergent in the region-l6, regions 15 and 16 extending respectively below and above horizontal plane 17 passing through the minimum area region of the stack opening 14.

The frame 11 includes circularly spaced upper and lower studs 18 and 19 interconnected in the region 20 as by appropriately spaced nails. The lower studs 19 are also connected through plates 21 with a metallic ring 22 having an L shaped cross section and extending around the frame for holding spreaders 23 in position, as shown in FIG. 3, bearing against the outer layer 24 of boards 13. Additional spreaders between the studs 18 and 19 are shown at 2.5, 26, 27 and 2d, and additional metal rings holding the spreaders 26 and 23 in position bearing against the inner layer of boards are shown at 29 and 3t). As will be explained, the rings 29 and 30 and spreaders 26 and 28, as well as the studs 18 act to hold or brace the inner layer 24 of boards against outward displacement, the bending of the boards about the central axis 12 causing them to exert outward pressure upon the studs 18, and the spreaders and rings bracing these studs.

The upper deck of the cooling tower is shown at 31, a tie down bolt 32 acting through the body 33 bearing against the spreader 25 and the boards 13 to hold the stack assembly on the upper deck 31. The weight of the stack is transmitted through the studs 19 to the deck 31.

The overlapping layers of boards 24, 34 and 35 have parabolic cross sections in vertical axial planes in the convergent region of the stack below the plane 17, whereas these same board layers have straight cross sections in vertical axial planes above the horizontal plane 17 as seen in FIG. 3. Furthermore, reference to FIG. 2 will show that the outer layer 24- of boards extends in an upwardly spiraling course in one direction about the axis 12 whereas the next inward layer 34 of boards extends in a spiral course in opposite direction about the axis, and it will be understood that the third or innermost layer of boards also extends in a spiral course but in the same direction as layer 24.

The boards in each layer extend very close to one another at locations 36 nearest the horizontal plane 17, whereas the same boards have increased spacing therebetween above and below the plane 17, as seen at 37 and 33. However, the stack wall is made relatively air-tight by the successive layering of the boards superimposed upon one another to cover the openings between the boards in each layer. Furthermore, opposite spiraling of the boards of successive layers greatly strengthens and makes rigid the entire stack assembly, which becomes virtually an assembly of braces interlocked with one another with nails passing therethrough and into the studs, as for example as shown at 39 in FIG. 3. Shear loading is exerted against these nails by the boards curving about the central axis 12 in the upper diverging regions of the stack, such shear loading preventing outward withdrawal of the nails due to the extreme frictional forces generated by the shear.

It is a prime feature of the invention that the boards in the layers 24, 34 and 35 below the plane 17 and forming the upwardly convergent lower portion of the stack are substantially straight in their lengthwise direction. This is made possible by relating their lengthwise angularity, with respect to the horizontal, to the parabolic curvature of the stack wall as determined by the inner sides of the studs 1b to which the boards are nailed.

aor'aoos Thus, in these regions of sharpest curvature as viewed in FIG. 3, the easiest assembly of the boards to the studs 19 occurs by reason of the boards remaining substantially straight throughout their lengths, only a slight warping of the boards about their length axes being necessary to conform them to the desired parabolic curvature during assembly. For the stack proportions illustrated, an approximate 30" angularity of the boards with respect to the horizontal, as indicated in FIG. 2, produces the desired straight lengthwise extents of the boards in the upwardlyconverging regions of the stack. It is understood of course, that the stack proportions may be varied to produce a somewhat different angularity of the boards with respect to horizontal, and therefore the 30 angularity mentioned is typical only of a representative construction.

FIGS. 1 and 3 show the fan blades 45 extending in the plane 17 for displacing air upwardly through the stack for fan rotation. Also shown in FIG. 1 are lines 46 indicating the terminations of successive boards in a given .layer, it not being necessary that the boards continue uninterrupted from the bottom to the top of the stack.

1 claim:

1.,An improved cooling tower stack assembly, comprising a frame having a substantially vertical central axis, and elongated strips carried by the frame defining a venturi shaped axial opening and extending about said aXis, those portions of said strips defining the converging portion of said opening extending with angularity to the horizontal and also being lengthwise substantially straight, the stack opening having minimum cross sectional area transversely of said axis in a region intermediate the convergent and divergent portions of said opening, said strips extending in inner and outer layers, outer layer strips being spaced apart at locations along their lengths and inner layer strips covering said spaces, the stack opening also having axially spaced equal cross sectional areas transversely of said axis and within said convergent and divergent positions of 'said opening, said equal areas being at unequal distances from said minimum area region.

2. The invention as :defined in claim 1 in which said strips comprise boards and said ,frame is at the outside of said boards.

3. The invention as defined in claim 2 in which those portions of said boardsdefining the divergent portion of said opening have lengthwise curvature about said axis.

4. .An improved cooling tower stack assembly, comprising a frame having a vertical central axis, and inner and outer layers of elongated boards attached to the frame defining a venturi shaped axial opening and extending about said axis, said opening having an upwardly convergent lower portion and an upwardly divergent upper portion, outer layer boards being spaced apart at locations along their major extents and inner layer boards covering spaces between the outer layer boards, those portions of said boards defining the converging portion of said opening extending with angularity to the horizontal and also being lengthwise substantially straight, the stack opening having minimum horizontal cross sectional area in a region intermediate the convergent and divergent portions of said opening, the stack opening also having vertically spaced equal cross sectional horizontal areas within said convergent and divergent portions of said opening, said equal areas being at unequal vertical distances from said minimum area region.

5. The invention as defined in claim 4 in which those portions of said boards forming the upwardly convergent lower portion of said opening have substantially parabolic cross sections in axial vertical planes.

6. The invention as defined in claim 4 in which those portions of said boards forming the upwardly divergent upper portion of said opening have lengthwise curvature about said central axis.

7. The invention as defined in claim 4 in which the inner and outer layers of boards extend lengthwise in opposite directions about said axis.

8. The invention as defined in claim 4 in which said frame is at the outside of the boards and includes circularly spaced upright supports and horizontally extending ring means bracing said supports against the outward pressure exerted by the boards forming the upwardly diverging upper portion of said opening.

References (Cited in the file of this patent FOREIGN PATENTS 5,961 Norway Jan. 16', 1898 329,715 Great Britain May 26, 1930 586,020 Germany Oct. 14, 1933 168,643 Switzerland July 2, 1934 OTHER REFERENCES Engineering Descriptive Geometry (Rowe), April 1949, pp. 154 and 155. 

1. AN IMPROVED COOLING TOWER STACK ASSEMBLY, COMPRISING A FRAME HAVING A SUBSTANTIALLY VERTICAL CENTRAL AXIS, AND ELONGATED STRIPS CARRIED BY THE FRAME DEFINING A VENTURI SHAPED AXIAL OPENING AND EXTENDING ABOUT SAID AXIS, THOSE PORTIONS OF SAID STRIPS DEFINING THE CONVERGING PORTION OF SAID OPENING EXTENDING WITH ANGULARITY TO THE HORIZONTAL AND ALSO BEING LENGTHWISE SUBSTANTIALLY STRAIGHT, THE STACK OPENING HAVING MINIMUM CROSS SECTIONAL AREA TRANSVERSELY OF SAID AXIS IN A REGION INTERMEDIATE THE CONVERGENT AND DIVERGENT PORTIONS OF SAID OPENING, SAID STRIPS EXTENDING IN INNER AND OUTER LAYERS, OUTER LAYER STRIPS BEING SPACED APART AT LOCATIONS ALONG THEIR LENGTHS AND INNER LAYER STRIPS COVERING SAID SPACES, THE STACK OPENING ALSO HAVING AXIALLY SPACED EQUAL CROSS SECTIONAL AREAS TRANSVERSELY OF SAID AXIS AND WITHIN SAID CONVERGENT AND DIVERGENT POSITIONS OF SAID OPENING, SAID EQUAL AREAS BEING AT UNEQUAL DISTANCES FROM SAID MINIMUM AREA REGION. 